Nowadays, communications spanning across multiple networks commonly occur. For example, via VOIP and PSTN networks, a computer user can initiate a voice call to, and communicate with a telephone user. A communication path, connecting two or more users across several networks, is sometimes established and maintained during a communication. Along the communication path, jitter buffers are often employed to maintain or improve the quality of communication.
Jitter buffers, however, can overflow or underflow, resulting in communication quality deterioration. In the case of an overflow, data packets arrive at a jitter buffer that is fully occupied and are dropped, resulting in unnecessary data loss. In the case of an underflow, data packets that are necessary to maintain a steady data flow are withheld from further transmission in the jitter buffer resulting in “broken” communication. It is therefore desirable to determine jitter buffer capacity within communication networks, especially along a communication path. However, jitter buffer capacity is difficult to predict because communication paths, especially those involving PSTN networks, are often constructed on the fly. Also, due to the fact that a communication path may span several networks, some of which have different owners, it is simply not possible to directly determine jitter buffer capacity across the entire communication path. Despite these difficulties, users still expect their communication with other users to be smooth and effective.
Given the above background, what is needed are methods for determining quality of service, including jitter, across communication networks used to host a communication path.